Method and agent for recovery of oxidized ores



-Patented May 10, 1932 UNITED STATES PATENT OFFICE STUART A. FALOONER, OF ELIZABETH, AND LUDWIG J. CHRISTMAN N, JERSEY CITY, NEW JERSEY, ASSIGNOBS TO AMERICAN CYANAMID COMPANY, OF NEW YORK, N. Y.,

A CORPORATION OF MAINE METHOD AND AGENT FOR RECOVERY OF OXIDIZED ORES No Drawing. Application filed June 1,

The object of this invention is the separation of minerals, especially of oxide minerals, from ores containing the same by froth flotation.

Manyreagents are known which are promoters for sulfide ores but not all sulfide reagents are effective in the flotation of socalled oxidized minerals. On the other hand, reagents for oxidized minerals will, in general assist in the flotation of sulfides.

By an oxide mineral We mean one composed of a heavy metal such as lead, zinc, copper, etc., in connection with elements or groups of elements other than sulfur.

It has been known that mercaptobenzothiazole possessed promoter properties for assisting in the flotation of oxide minerals but it is too insoluble as such and is best used in the form of its sodium or potassium salt. Although such salts are of some value in the flotation of oxidized ores, we have found that by dissolving mercaptobenzothiazole in a so lution of sodium sulfide it is possible to obtain much better flotation results than when the sodium or potassium salt of mercaptobenzo- 'thiazole is used either alone or in conjunction with sodium sulfide or with the polysulfides Na s Na s Na s or Na s A series of tests was run on an ore from Africa. The ore contained a considerable amount of the copper as chrysocolla. The analysis of the sample wasas follows:

Per cent Total copper 11. 28 Non-sulfide copper 10.48 Iron 4. 80 A1 0 4. 33 Lead Trace Zinc Trace MgO 1. 41 C1 Trace Sulfur 0.92 Manganese 0.088 Insoluble 65. 70 Gold Trace Silver Trace ing through a set of rolls to minus 10 mesh 1931. Serial N0. 541,528.

ore and 600 cc. of water were ground in a steel laboratory rod mill for a period of 18 minutes.

A screen analysis showed:

Mesh Weight 65 100 0. 50

The ground charge was transferred to a laboratory subaeration type of flotation machine and diluted to 22% solids. A total time of float of 18 min. was used but the reagents were added in stages.

\Vhen the sodium salt of mercaptobenzothiazole was used alone, very poor results were obtained. used together'with the sodium salt of mercaptobenzothiazole, the results were improved. The use of sodium poly sulfides in conjunction with sodium mercaptobenzothiazole gave about the same results as sodium sulfide. However, when mercaptobenzothiazole dissolved in sodium sulfide solution was used, greatly improved results were obtained, the increase in recovery of copper being as high as 10% over that obtained with the combination of the sodium salt of mercaptobenzothiazole and sodium sulfide.

The following table outlines, in general, the procedure followed, giving the time of the flotation treatment, the amounts of reagents used, and the intervals at which they were added.

Reagents added, pounds per ton of ore minutes Reagent Start 2 4 6 8 10 12 14 16 Sodium salt of mercaptobenzothiazolennn 0.50 0. 25p. 25 0.25 0.25 0.25 0.25 0.25 0.25 Sulfidizing agent 0.50 0. 25 0.25 0. 25 0. 25 0.25 0 25 0. 25 0. 25 Oleic acid 0.046 0.023 0.046 Pine nil 0.021 0.02] 0.021-

When mercaptobenzothiazole dissolved in \Vhen sodium sulfide was sodium sulfide was used, the first addition was equivalent to one pound of combined reagent per ton and the additions at two minute intervals were equivalent to 0.5 pounds per ton.

The following table gives the comparative results obtained with the sodium salt of mercaptobenzothiazole and the various sulfidizing reagents:

Reagents: Pounds per ton Products %Cu 55 s: ca w g fie Es 8 .5 s g 6 5?: 551 a g s -3 as 0' a: o m 32 0 s: w o: a: (c s o i=1 0 a 2 2 z z z A 4 s A 6% solution of the above reagent is prepared by dissolving three parts by weight of mercaptobenzothiazole in 100 parts of water containing three parts by weight of fused sodium sulfide.

From the table it is readily, seen that the v results obtained with mercaptobenzothiazole dissolved in sodium sulfide are by far the best by from 6.1% to 12.1% additional copper recovery.

On another sample of oxidized ore in which the copper mineral was largely malachite, an experiment was run under the same conditions as above and the following results were obtained.

Pounds per ton Cu iii zia tiigl 321 33 red aig g i benzothia- N828 covers Heads Cone. Tails I Nags While we do not know with certainty the reasons for the effectiveness of our composition as a promoter of flotation we believe that the combination forms sodium hydrosulphide which acts as a sulfidizing agent and which at the same time imparts only a low degree of alkalinity. This is of great advantage, in that it minimizes the tendency to form soluble compounds of the heavy metals with al-.. kalis and thus render such metals more amenable tothe flotation o eration. Furthermore, our invention provides a most inexpensive and conirenient means for solubilizing mercaptobenzothiazole and at the same time ohtaming the available sodium hydrosulphide.

Although We have described our invention setting forth a single embodiment thereof it is apparent that many variations in composition and in procedure may be made within the scope of our invention. For example, we may use dlfferent proportions of mercaptobenzothiazole and of sodium sulfide with fide, potassium sulfide and the like may be used. Our invention is not limited to the treatment of'copper ores but is applicable to the treatment of ores of other metals, such as lead, zinc and the like and particularly ores of oxidized character.

WVhat we claim is:

1. In the flotation concentration of ores, the method which comprises adding to the flotation circuit as a promotor a mixture of mercaptobenzothiazole and an alkali metal sulphide.

2. In the flotation concentration of ores, the method which comprises adding to the flotation circuit as a promotor a mixture of mercaptobenzothiazole and sodium sulphide.

3. In the flotation concentration of ores, the method which comprises adding to the flotation circuit as a promotor, a mixture of sodium mercaptobenzothiazole and an alkali metal hydrosulphide.

metal hydrosulphide.

8. A composition of matter comprisingsodium mercaptobenzothiazole and sodium hydrosulphide.

In witness whereof, we have hereinto subscribed our names this 27th day of Ma 1931.

STUART A. FALCONE LUDWIG J. CHRISTMANN. 

